the medical examiner initially ruled khan died of natural causes. but after concerns, siblings demanded more tests, authorities found a lethal amount of cyanide in his blood, turning this case into a homicide investigation. >> when we found out there was cyanide in his blood, after the toxicology report, somebody that to kill him. >> reporter: so far, police have named no suspects. but they did question his widow for hours. you can't tell us a few words on camera? ansari, working at the couple's dry cleaning business, declined to speak to abc news on camera. but says the night before her husband died, she cooked a traditional indian meal for him. and says everything seemed okay. >> positively, she had nothing to do with her husband's death. >> reporter: ansari is now locked in a legal battle with khan's family over his estate. he didn't have a will. but he had more than $1 million in lottery winnings and business holdings, all at stake. court documents show there are doubts that the couple was even legally married. authorities are one step closer to